Followers

Sunday, March 30, 2008

Europe-wide radio net in aliens search

Scientists are finalising plans to link radio wave detectors in five countries and create a device sensitive enough to pick up signals from worlds the other side of the galaxy.

By connecting banks of detectors in fields across Britain, France, Holland, Sweden and Germany, astronomers aim to create a radio telescope that will have the accuracy of a machine the size of Europe. They believe it could solve some of the universe's most important secrets - including the discovery of radio broadcasts from intelligent extraterrestrials.

'This system works by collecting radio waves over a range of frequencies,' said cosmologist Robert Nichol of Portsmouth University. 'These can then be analysed using arrays of computers which can identify patterns from the data streaming from our detectors.

'Some of these signals will reveal information about the early universe, for example. However, broadcasts by alien intelligences would also be revealed by our computers because we will, primarily, be collecting radio signals. Signals that have regular patterns will give themselves away as the possible handiwork of extraterrestrials. Such work is a bonus, however. The main work of the system is basic research,' added Nichol.

The project - known as Lofar (low frequency array) - was launched in Holland several years ago, but has attracted the attention of other European astronomers. All have agreed to build their own banks of detectors, which can then be linked to those in Holland. Britain is committed to building one set, while requests for money for another three have been put to research councils.

Several sites for Britain's first array are being considered, although most scientists expect it to be built at Jodrell Bank in Cheshire, where the giant radio dish is threatened with closure because of funding cuts. By building the Lofar antenna, which represents the future of radio astronomy, ground-breaking research can continue at the site, say scientists.

Lofar arrays exploit the fact that metals pick up radio waves and convert them into weak electric signals. In the past, dishes were pointed at heavenly objects so that their radio waves could be focused on a central receiver and generate a signal strong enough to be analysed.

Lofar uses a very different approach. 'Instead of moving a huge dish around the sky and pointing it at a star or galaxy or nebula, you simply cover a field with sheets of metal. The metal will pick up radio waves from all over the sky,' said Nichol, who this month was awarded a €50,000 Marie Curie prize by the European Union for his research. 'You then analyse these with banks of computers and, by carefully writing your software, you can pinpoint the object you want to study.

'The crucial point is that the more arrays you have, the more radio waves you collect, so Lofar becomes more sensitive. And if you have arrays far apart from each other, you can resolve distant objects with greater and greater precision.'

In other words, instead of using complex hardware to target objects in the sky, astronomers will exploit highly sophisticated 21st-century computer software to select and study their targets. Thus the steerable radio telescope at Jodrell Bank could be replaced by a series of metal plates the size of a football pitch.

'We will be looking for all sorts of different things with Lofar,' added Nichol. 'We will make surveys of the skies to look for unexpected events; for things that go bump in the night, as it were. We will also be able to study the universe's childhood years. We know a lot about the Big Bang, when the universe was created 13 billion years ago, and a lot about it now. But its early childhood years, around 500 million years after the Big Bang, remain a mystery.

'Why and how did stars form out of atoms that then permeated the cosmos? Lofar will help us work that out.'

Other scientists, including Lyndsay Fletcher at Glasgow University, intend to use Lofar to study objects much nearer to home, such as the Sun. 'Radio emissions pour from the Sun at all sorts of frequencies, each characteristic of a different physical process that is going on inside it,' said Fletcher. 'Lofar will give us a completely new method for understanding what goes on inside our own Sun.'